Sheet metal working electrode and handpiece

ABSTRACT

A sheet metal working electrode handpiece is described for delivering electric current from a source of electrical energy to a selected location on a sheet metal workpiece. The electrode has an electrically insulated handle with an electrical conductor having a connector for electrical contact with a source of electrical energy. A control switch on the handle provides electrical connection to the source of electrical energy to control delivery of electrical energy to the conductor. A first electrode adapter is provided on the handle, oriented along a first axis. A second electrode adapter is also provided on the handle, oriented along a second axis substantially normal to the first axis. Any one of several sheet metal engageable electrodes may be removably mounted to at least one of the adapters. One such electrode is a dent pulling electrode which includes a shank, threaded at one end to be received in one of the adapters. The shank is formed of carbon steel and includes a flat reduced end for engagement with a workpiece. A torque surface is situated between the shank ends to facilitate securing the electrode to the handpiece or engagement with a tool used to twist the electrode on its axis. Other electrodes include a copper shank, spherical end heat shrinking electrode, a spot welding electrode, a nail head welding electrode, and a chrome strip clip welding electrode.

RELATED APPLICATIONS

The present application is a continuing application of co-pending U.S.patent application Ser. No. 08/110,571, filed Aug. 23, 1993.

TECHNICAL FIELD

The present invention relates to welding, forming, or shaping sheetmetal using hand-held electrodes and handpieces for holding andelectrically isolating the user from the electrode.

BACKGROUND OF THE INVENTION

Specialized electrical discharge devices have been developed for sheetmetal working, for shaping and fastening sheet metal workpiecestogether. Tools, for example, have been developed for spot welding sheetmetal pieces together. Other tools have been developed for attachingpullers to vehicle body dents, to aid in pulling the dents outwardly.Still other tools have been developed for heating and shrinking smallareas on sheet metal panels to aid in removing dents or bumps. Each taskrequires a different electrode and attachment to the welder powersource.

The present invention solves the problem by provision of a singlehandpiece capable of mounting any of several electrodes used forindividual tasks. The present invention also fills the need for a singlehandpiece and electrode with capability for mounting the electrode ateither of two different locations on the handpiece.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are illustrated herein withreference to the accompanying drawings, in which:

FIG. 1 is a perspective view of an electrode handpiece exemplifyingfeatures of a first preferred form of the present invention connected toa source of electrical energy;

FIG. 2 is a longitudinal sectioned view taken along line 2--2 in FIG. 1;

FIG. 3 is a front end elevation view;

FIG. 4 is a rearward end elevation view;

FIG. 5 is a partially sectioned side view showing a sheet metal dentpuller stud mounted to the handpiece;

FIG. 6 is a partially sectioned side view showing a spot welderelectrode mounted to the handpiece;

FIG. 7 is a partially sectioned side view showing a chrome clip weldingelectrode mounted to the handpiece;

FIG. 8 is a partially sectioned side view showing a sheet metalshrinking electrode mounted to the handpiece;

FIG. 9 is a partially sectioned side view showing a nail head weldingelectrode mounted to the handpiece; and

FIG. 10 is a detail view of a preferred sheet metal dent pullingelectrode.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws "to promote the progressof science and useful arts" (Article 1, Section 8).

A preferred embodiment of the present sheet metal working electrodehandpiece is designated in the accompanying drawings by the referencenumeral 10. The handpiece 10 is used as diagrammatically shown in FIG. 1to deliver welding current from a source of electrical energy 11 to aselected location on a sheet metal workpiece 12. Various attachments areshown in the drawings and will be described in detail below.

The handpiece 10 includes an electrically insulated handle 15. Thehandle includes a nonconductive elongated hand grip section 16 that istubular, housing a switch base 17. A conductor guard 18 of an inverted"U" shaped cross-section is mounted to and spaced from a hand gripsection 16 by non conductive spacers 19.

An electrical conductor 20 is secured by mounting bolts 21 within thespacers 19 to the switch base 17, electrically isolated from the handgrip section 16 by the nonconductive handle material. The conductor 20is advantageously formed of an electrically conductive metal such asaluminum, in the form of an elongated bar. The conductor 20 is housedwithin the inverted "U" shaped conductor guard 18, along the lengththereof. Legs of the guard 18 project the adjacent sides of theconductor 20 (FIG. 4) to insulate the conductor from undesiredelectrical contact.

A connector 23 (FIG. 2) is provided on the conductor 20 for electricalcontact with a source of electrical energy 11 (diagrammatically shown inFIG. 1). Conventional welding cable may be used for such connection.Connector 23 may thus simply be provided as a socket formed in one endof the conductor 20. One or more set screws 25 are provided in theconductor 20, communicating with the cable receiving socket, forsecuring and making electrical contact with the cable.

A control switch 28 is provided on the handle for electrical connectionto the source of electrical energy to control delivery of electricalenergy to the conductor 20 through the welding cable. The switch 28advantageously includes a conventional micro switch 29 mounted within arecess in the switch base 17. The micro switch includes an actuatorplunger 30 that is biased to hold the switch a normally open condition.

Switch 28 also includes a pivoted actuator button 34, mounted to theswitch base 17 with an actuator surface projecting over the microswitch.A stop surface 35 (FIG. 2) is provided along the switch base 17, betweenthe pivot for the actuator button 34 and the microswitch plunger 30. Thesurface 35 is positioned in relation to the microswitch plunger 30 tostop inward movement of the actuator beyond that required to move theswitch to a closed condition. The stop surface 35 thus prevents damageto the switch by forcible impact against the actuator button 34.

A first electrode adapter 40 is provided on the handle, oriented along afirst axis X. As exemplified in FIG. 2, the first axis is parallel tothe hand grip section 16. The preferred first adapter 40 includes aconductive socket member threaded into the end of the conductor at theend thereof. A locknut 42 holds the adapter securely on the conductor20.

Adapter 40 includes an axial bore 41 (FIG. 1) that opens in a forwarddirection along axis X. A spring clip keeper 45 is mounted between thelocknut 42 and conductor 20. The outward end of keeper 45 is bent towardthe axis X to engage and hold selected electrodes within the smooth,unthreaded bore.

A second electrode adapter 50 is also provided on the handle, orientedalong a second axis Y that is substantially normal to the first axis X.The adapter 50 includes a conductive socket member threaded into the endof the conductor on the bottom side thereof, and substantially centeredlongitudinally along the hand grip section 16. A locknut 52 holds theadapter securely on the conductor 20.

The second adapter 50 includes an axial bore 51 (FIG. 5) that opens atthe bottom end of the socket member in a downward direction along axisY. The bore 51 is threaded to threadably receive an electrode shank.

The adapter 50 in a preferred form, is elongated, extending severalinches downwardly from the conductor 20. The length (along axis Y) issufficient to allow the adapter to be received within depressions insheet metal (as in vehicle body dents). It is preferably constructed ofcopper.

A sheet metal engageable electrode is removably mountable to at leastone of the adapters. Several preferred electrodes are provided, each forperforming a particular function. The examples shown include a noveldent pulling electrode 55 (FIGS. 5 and 10), a metal shrinking electrode60, a spot welding electrode 65, and nail (FIG. 9) and chrome clip (FIG.7) welding electrodes 70, 75.

The preferred novel dent pulling electrode 55 (FIG. 5) includes anelongated shank 56, formed of medium carbon alloy steel, equivalent toan SAE grade 8 bolt shank, having a Rockwell hardness of approximatelyc33/c39. The preferred shank is partially threaded at one end 57. Theopposite end 58 is tapered to a flat sheet metal engaging tip ofapproximately 0.06 inches in diameter. A torque surface is providedalong the shank between the ends 57, 58, advantageously at thetransition to the threaded section of the shank 56. Depending on theshank size, the threaded portion may either be threaded into the secondelectrode adapter socket or slidably engaged in the first electrodesocket.

In a preferred form, the torque surface is provided by a lock nut 59threaded onto the threaded part of the shank. The nut may be jammedagainst the unthreaded part of the shank, to lock itself on the shankagainst rotation. Flats on the nut 59 provide gripping surfaces for awrench (not shown) which can be used to twist the electrode on its axis,disengaging it from a sheet metal surface where it becomes welded duringuse. Alternatively, the nut may be loose on the threaded portion, to betightened against the adapter 50, thereby securing the electrode to thehandpiece.

The metal shrinking electrode 60, in a preferred form (FIG. 8), isconstructed of copper and includes a shank 61 adapted to be slidablyreceived in the axial bore of the first electrode adapter 40. Theoutward end of the shank 62 is spherical and smooth to avoid welding ofthe electrode to the sheet metal workpieces. The tangential pointcontact between the copper spherical surface promotes surface heating ofthe sheet metal in the vicinity of the point contact, which then effectsshrinkage in the adjacent areas as the metal cools.

The spot welding electrode 65 (FIG. 6) is somewhat structurally similarto the dent pulling electrode 55, with the exception that the preferredelectrode material is copper and the reduced flat tip 66 of electrode 65has a somewhat larger diameter, of approximately 0.1 inches. Its shank67 is smooth, to be received in the first electrode adapter 40.Electrode 65 is also formed of copper to present excellent conductivityand to resist self welding to the sheet material. The flat tip 66 servesto contact and press sheet metal workpieces together and to conduct andconcentrate electrical flow in amounts sufficient to fuse the juxtaposedsheets of material together in the vicinity of the tip contact.According to need, the electrode may be made to slidably fit adapter 40or be threaded to fit or even to replace the second adapter 50.

The nail welding electrode 70 (FIG. 9) and the chrome clip weldingelectrode 75 (FIG. 7) both include copper shanks with central bores 71,76 formed in outward tips 72, 77 to receive shanks 73 of headed nails orheaded ends 78 of chrome strip mounting clips. The chrome clip weldingelectrode 75 also includes axial slots 79 that allow the bore 76 to besprung open to yieldably receive the clip heads 78. The electrodes 70,75 may be mounted selectively in either first or second adapter 50, butfind most prevalent use in the first electrode adapter 40.

In use the present handpiece is attached to a source of electricalenergy, such as the power source 11 specifically provided for suchhandpieces and electrodes and produced by "Dentmaster Inc." of SpokaneWashington. This is done simply by attaching a power cable from thewelder to the connector on the handpiece, using the set screws to secureand make full electrical contact.

Next the control switch 29 is connected to the appropriate timercircuitry of the welder unit, such that actuation of the control switchwill close a circuit for a selected amount of time, and allow current toflow to the handpiece conductor 20 and out through the electrodecurrently contacting a conductive workpiece.

The handpiece, once connected to the source of current and controls, isready for use.

If used as a dent puller, a ground wire is mounted to the sheet metalworkpiece and a dent pulling electrode 55 is attached to the handpiece10, preferably threaded to the second electrode adapter 50. Next, thehandle 15 is grasped and maneuvered so the flat pointed end of theelectrode 55 is pressed firmly against the dented sheet metal,preferably in the deepest part of the dent and with the flat end surfaceflush against the dented surface. Now the control switch 29 may beactivated, causing the selected timed current flow through the electrode55 and into the workpiece.

Because of the small contact area, timed discharge, and high currentflow, the carbon steel tip of the electrode quickly welds itself to theworkpiece. Now the handpiece handle may be used to pull against theelectrode 55, and the engaged area of the workpiece, causing the dent tobe pulled outwardly. If the electrode is securely threaded to thehandpiece and the nut has been tightened against the threaded adapter50, the handpiece 10 itself may be used to apply the separating torque.Alternatively, when the dent has been pulled, a wrench may be attachedto the nut 59 on the electrode 55. Torque may then be applied about theelectrode axis to snap the electrode weld and allow separation of theelectrode from the workpiece.

The remaining attachments operate similarly as described above, with theexception that smooth shank electrodes are simply slid into the socketof the first adapter. Use is determined by the work to be accomplished,but basically involves engagement of the electrode with the workpieceand actuation of the control switch 29.

In compliance with the statute, the invention has been described inlanguage more or less specific as to methodical features. It is to beunderstood, however, that the invention is not limited to the specificfeatures described, since the means herein disclosed comprise preferredforms of putting the invention into effect. The invention is, therefore,claimed in any of its forms or modifications within the proper scope ofthe appended claims appropriately interpreted in accordance with thedoctrine of equivalents.

We claim:
 1. A sheet metal working electrode handpiece, comprising:ahand grip; an electrical conductor attached to the hand grip; and twodistinct electrode adapters mounted to and in electrical connection tothe conductor.
 2. A sheet metal working electrode handpiece fordelivering welding current from a source of electrical energy to aselected location on a sheet metal workpiece, wherein the electrode iscomprised of:an electrically insulated handle; an electrical conductorfor electrical contact with a source of electrical energy, mounted toand electrically isolated from the handle; a control switch connected tothe conductor for electrical connection to the source of electricalenergy to control delivery of electrical energy to the conductor; afirst electrode adapter on the electrical conductor, oriented along afirst axis; a second electrode adapter on the electrical conductor,oriented along a second axis spaced apart from the first axis; and asheet metal engageable electrode removably mountable to at least one ofthe electrode adapters including an elongated conductive shank extendingto an end and including a gripping surface on the shank in a fixedposition thereon.
 3. A sheet metal working electrode handpiece asclaimed by claim 1, wherein the handle is elongated and wherein thefirst axis extends longitudinally with respect to the elongated handle.4. A sheet metal working electrode handpiece as claimed by claim 1,wherein the handle is elongated along a handle axis; andwherein thesecond axis is distinct from the first axis and the handle axis.
 5. Asheet metal working electrode handpiece as claimed by claim 1, whereinthe handle is elongated along a handle axis and wherein the second axisis substantially perpendicular to the handle axis.
 6. A sheet metalworking electrode handpiece as claimed by claim 1, wherein the first andsecond adapters are comprised of electrically conductive socket membersfor releasably receiving an electrode.
 7. A sheet metal workingelectrode handpiece as claimed by claim 1, wherein the electrode iscomprised of:an elongated shank of electrically conductive metal;wherein the shank includes a sheet metal engaging tip.
 8. A sheet metalworking electrode handpiece as claimed by claim 1, further comprising asheet metal shrinking electrode, including:an elongated copper shankslidably receivable in one of the electrode adapters; a semi-sphericalhead on the elongated copper shank.
 9. A sheet metal working electrodehandpiece as claimed by claim 1, further comprising a spot weldingelectrode formed of copper and including:an elongated shank extending toa pointed end.
 10. A sheet metal working electrode handpiece as claimedby claim 1, wherein the electrode is comprised of:an elongated steelshank; and a bolt head on the shank in fixed position thereon.
 11. Asheet metal working electrode handpiece as claimed by claim 1, whereinthe electrode is comprised of:an elongated shank formed of a SAE grade 8bolt shank and extending from a socket receiving end to a pointed end;and a bolt head on the shank in fixed position thereon between thepointed end and the socket receiving end.
 12. A sheet metal workingelectrode handpiece as claimed by claim 1, further comprising a nailwelding electrode, including:an elongated shank for attachment to one ofthe electrode adapters formed of electrically conductive material andextending between a socket receiving end and an outward end, andincluding an axial bore formed inward from the outward end.
 13. A sheetmetal working electrode handpiece for delivering welding current from asource of electrical energy to a selected location on a sheet metalworkpiece, wherein the electrode handpiece is comprised of:anelectrically insulated handle including an elongated hand grip section;an elongated electrical conductor electrically isolated from the handgrip section longitudinally in spaced juxtaposition relative to the handgrip section; a connector connected to the electrical conductor forelectrical contact with a source of electrical energy; a control switchconnected to the conductor for electrical connection to the source ofelectrical energy to control delivery of electrical energy to theelectrical conductor; a first electrode adapter on the electricalconductor opening outwardly along a first axis; a second electrodeadapter on the electrical conductor opening outwardly along a secondaxis disposed independently of the first axis, the second axisintersecting the handle length.
 14. A sheet metal working electrodehandpiece as defined by claim 13 wherein the first and second electrodeadapters protrude outwardly from the electrical conductor.
 15. A sheetmetal working electrode handpiece for removably mounting an electrodeand for delivering welding current from a source of electrical energythrough the electrode to a selected location on a sheet metal workpiece,wherein the electrode handpiece is comprised of:an electricallyinsulated handle including an elongated hand grip section; an electricalconductor electrically isolated from the hand grip section forelectrical contact with a source of electrical energy and including aswitch base adjacent the hand grip; a spacer separating a portion of theconductor from the hand grip section in substantially parallel andjuxtaposed relation thereto; a control switch on the switch base forelectrical connection to the source of electrical energy to controldelivery of electrical energy to the electrical conductor; a firstelectrode adapter on the electrical conductor, oriented along a firstaxis that is longitudinally oriented with respect to the hand gripsection; and a second electrode adapter on the electrical conductor,oriented along a second axis disposed independently of the first axis.16. A sheet metal working electrode handpiece as defined by claim 15wherein the handpiece is further comprised of an electricallynonconductive conductor guard mounted to the spacer for housing aportion of the electrical conductor.
 17. A sheet metal working electrodehandpiece as defined by claim 15 wherein the first and second electrodeadapters protrude outwardly from the electrical conductor.
 18. A sheetmetal working electrode handpiece for removably mounting an electrodeand for delivering welding current from a source of electrical energythrough the electrode to a selected location on a sheet metal workpiece,wherein the electrode handpiece is comprised of:an elongatedelectrically insulated handle including an elongated hand grip section;an electrical conductor mounted to the hand grip section andelectrically isolated therefrom; the electrical conductor in spacedjuxtaposition relative to the hand grip section; a connector on theelectrical conductor for electrical contact with a source of electricalenergy; a control switch for electrical connection to the source ofelectrical energy to control delivery of electrical energy to theelectrical conductor; a first electrode adapter on the electricalconductor located along a first axis that is longitudinally orientedwith respect to the elongated hand grip section; a second electrodeadapter on the electrical conductor, located along a second axisdisposed independently of the first axis and intersecting the hand gripsection; and wherein at least one of the electrode adapters includes anelectrode receiving socket for receiving an electrode.
 19. A sheet metalworking electrode handpiece as defined by claim 18 wherein the secondelectrode adapter is approximately centered along the length of the handgrip section.
 20. A sheet metal working electrode handpiece as definedby claim 18 wherein the first and second electrode adapters are mountedto the electrical conductor and project outwardly therefrom.